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Terminology
Dominance
Probability
Genetics Problems
Potpourri
100
Alternative versions of a gene are called?
Alleles
100
A cross between homozygous purple-flowered and homozygous white-flowered pea plants results in offspring with purple flowers. This demonstrates
Complete dominance
100
What is the probability that a couple has the following sequence of children: boy, girl, boy?
1/8
100
Achondroplasia is a form of dwarfism caused by a rare dominant allele. Homozygous dominant individuals do not survive. A couple, both with Achondroplasia, decide to have a child. What is the probability that the child will also have Achondroplasia.
1/2. There is actually 3/4 of a chance but AA will die.
100
Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. What does this tell you about the genotypes of the parents?
They are both heterozygotes.
200
Two identical alleles. What would be the genotype(s)?
Homozygous, aa or AA
200
A single gene to have multiple phenotypic effects. Give and example.
Pleiotropy, Sickle Cell Anemia
200
When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive phenotype?
50%
200
A orange female cat and a black male cat have kittens. What are the possible colors for the male and female kittens in this cross?
Tortoise shelled females and orange males.
200
Mendel's observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division?
Anaphase I
300
Physical appearance.
Phenotype
300
The phenotype of the heterozygote differs from the phenotypes of both homozygous parents.
Incomplete dominance, Snap Dragon color
300
In a cross AaBBCc × AaBbCc, what is the probability of producing the genotype AABBCC?
1/32
300
In a particular family, one parent has Type A blood, the other has Type B. They have four children. One has Type A blood, one has Type B blood, one has Type AB blood, and the last has Type O blood. What are the genotypes of all six people in this family? Genotypes are expressed as I^A, I^B, and ii).
Parent type A Parent type B Child type A Child type B Child type AB Child type 0
300
How can we tell the genotype of an individual with the dominant phenotype?
Do a test cross
400
What is the difference between a monohybrid cross and a dihybrid cross?
A dihybrid cross involves organisms that are heterozygous for two characters and a monohybrid only one.
400
Two dominant alleles affect the phenotype in separate, distinguishable ways.
Codominance, ABO blood types.
400
In a cross aaBbDdEe × aaBbddEe, what is the probability of producing the genotype aabbddee?
1/32
400
In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red : 2 roan : 1 white?
roan x roan
400
Why are humans Humans are not good subjects for genetic research?
Generation time is too long Parents produce relatively few offspring Breeding experiments are unacceptable
500
Why are deadly diseases rarely dominant? Why will we never remove mutant alleles from our gene pool?
Individuals die before they reproduce. Mutant alleles are hidden in carriers.
500
A gene at one locus alters the phenotypic expression of a gene at a second locus.
Epistasis, lab coat color.
500
Skin color is inherited by polygenic inheritance. Each "dominant" capital gene produces one unit of color, so that a wide range of intermediate skin colors are produced, depending on the number of "dominant" capital genes in the genotype. A person that is AABBDD has the darkest skin color and a person that is aabbdd have the lightest. What is the probability of a couple that is AaBbdd x AaBbdd having a child with the fairest skin possible.
1/16
500
A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. What genotypes for the gametes are possible in this organism?
HT Ht hT ht
500
Explain why in most states, first cousin marriages are not legal?
Greater chance of genetically inherited diseases.